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113 lines
3.7 KiB
Groff
113 lines
3.7 KiB
Groff
.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)getpgrp.2 8.1 (Berkeley) 6/4/93
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.\"
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.TH GETPGRP 2 "16 January 1997" GNO "System Calls"
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.SH NAME
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.BR getpgrp
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\- get process group
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.SH SYNOPSIS
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.br
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#include <unistd.h>
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.sp 1
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pid_t
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\fB_getpgrp\fR (pid_t \fIpid\fR);
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.br
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pid_t
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\fBgetpgrp\fR (void);
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.SH DESCRIPTION
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.BR getpgrp
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returns the process group of the current process.
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.BR _getpgrp
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returns the process group of the process specified by
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.IR pid .
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.LP
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Process groups are used for distribution of signals, and
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by terminals to arbitrate requests for their input: processes
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that have the same process group as the terminal are foreground
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and may read, while others will block with a signal if they attempt
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to read.
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.LP
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This call is thus used by programs such as
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.BR csh (1)
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to create
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process groups
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in implementing job control.
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The
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.BR tcgetpgrp
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and
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.BR tcsetpgrp
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calls
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are used to get/set the process group of the control terminal.
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.SH RETURNS
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On success, the requested process group is returned. On failure, -1 is
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returned and
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.BR errno
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is set.
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.SH STANDARDS
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The
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.BR getpgrp
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function conforms to IEEE Std 1003.1-1988 (POSIX).
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.SH COMPATIBILITY
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This version of
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.BR getpgrp
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differs from past GNO (pre-v2.0.6) and Berkeley versions by not taking a
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.I "pid_t pid"
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argument.
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This incompatibility is required by
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POSIX 1003.1-88.
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.IP "From the POSIX 1003.1-88 Rationale:"
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4.3BSD provides a
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.BR getpgrp
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function that returns the process group ID for a specified process.
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Although this function is used to support job control, all known
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job-control shells always specify the calling process with this
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function.
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Thus, the simpler System V
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.BR getpgrp
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suffices, and the added complexity of the 4.3BSD
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.BR getpgrp
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has been omitted from POSIX.1.
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.LP
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The older version of
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.BR getpgrp
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which takes an argument is available as the non-standard function
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.BR _getpgrp .
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.SH SEE ALSO
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.BR job_control (2),
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.BR setpgid (2),
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.BR termios (4)
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.SH HISTORY
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The
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.BR getpgrp
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function call appeared in 4.0BSD.
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